This invention relates to reducing electrical signal interference which arises electrical connectors having closely spaced contacts. More particularly it relates to the reduction of cross talk induced by closely spaced contacts in Federal Communications Commission (FCC) type modular jacks and plugs and other signal connectors.
The FCC has adopted certain architectural standards with respect to electrical connectors utilized in the telecommunication industry so as to provide intermatability. The connectors that are most commonly utilized are FCC type modular plugs and jacks. The plug is terminated to a plurality of wires which may be connected to a telephone handset or other communication device. The corresponding jack is often mounted to a panel or printed circuit board which in turn is connected to a telecommunication network. The jack may also include a lead frame, whereby the printed circuit board is eliminated and a plurality of wires are terminated to the jack via insulation displacement contacts which are integral with the lead frame.
A typical FCC jack is described in U.S. Pat. No. 4,648,678 issued to Archer. The Archer jack includes a plurality of closely spaced parallel electrical contacts. Typically, the closely spaced parallel contacts are mounted to a nose piece as shown in FIG. 1. Nose piece 10 includes a plurality of contacts 12 mounted thereto. Contacts 12 are divided into pairs forming so-called signal pairs. Because these contacts are so closely spaced due to FCC constraints and are parallel to one another, pair to pair cross talk is induced. This cross talk is primarily due to capacitive and inductive couplings between adjacent conductors. Since the extent of the cross talk is a function of the frequency of the signal on a pair, the magnitude of the cross talk is logarithmically increased as the frequency increases and is commonly expressed as ten times the log of the ratio of the cross talk energy divided by the signal energy (decibels or DB).
As FCC modular jacks and plugs are utilized more in high frequency data and communication applications, cross talk, which arises in adjacent and parallel contacts within the jack, has become an industry problem. U.S. Pat. No. 5,299,956 issued to Brownell and Vaden, and assigned to Superior Modular Products, Inc., assignee of this invention, teaches the cancellation of the cross talk arising in the jack by utilizing a capacitance formed on the circuit board which is connected to the jack. U.S. Pat. No. 5,186,647 issued to Denkmann et al teaches of the reduction of cross talk in an electrical connector by crossing over conductors of a lead frame in an electrical connector. A design which incorporates some of the concepts taught by Denkmann et al is shown in FIG. 10.
While the Brownell/Vaden and the Denkmann approaches to cross talk reduction have significantly reduced cross talk and have met with substantial commercial success, there remains a need to further enhance the performance of FCC type connectors, particularly as frequencies increase.
U.S. Pat. No. 5,399,107 issued to Gentry et al shows a modular jack which achieves enhanced cross talk performance by utilizing alternating long and short electrical contacts so that not all portions of the adjacent contacts are immediately adjacent. The alternating Gentry contacts are illustrated in a simplified form in FIG. 2 as short contact 60 and long contact 62. However, the resiliency of the short contact 60 of Gentry is compromised due to its length.
Stewart Stamping Company sells a reduced cross talk connector where the reduction is achieved by the configuration of adjacent contacts, however, the adjacent contacts do not have major first bends in the same direction like the typical contacts shown in FIG. 1. In addition, the Stewart design reduces longitudinal balance.